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  • 1
    Electronic Resource
    Electronic Resource
    The effects of crystallographic orientation, interface type and growth kinetics on Ni distribution between olivine and its melt (1983)
    Springer
    Physics and chemistry of minerals 9 (1983), S. 167-172 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The effective distribution coefficient K eff of Ni between solid and liquid has been experimentally determined as a function of growth rates and crystallographic orientations for (Mg, Ni)2SiO4 crystals grown by the floating-zone method. Crystals were grown by the continuous mechanism at slow rates, but were faceted at high rates, which enables us to determine the dependence of K eff on orientations and on smooth versus rough interfaces. It has been verified that K eff of Ni becomes larger than the equilibrium value K o as the growth rate increases and that K eff of faceted «110» directions is larger than that of non-faceted higher index directions. The results can be qualitatively explained by the theories which treat the distribution of elements in relation to growth kinetics. Element distribution during the recovery process from rounded to faceted morphology is also analysed in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308374
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  • 2
    Electronic Resource
    Electronic Resource
    The pressure and temperature dependence of the elastic properties of single-crystal fayalite Fe2SiO4 (1988)
    Springer
    Physics and chemistry of minerals 16 (1988), S. 186-198 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The nine adiabatic elastic stiffness constants of synthetic single-crystal fayalite, Fe2SiO4, were measured as functions of pressure (range, 0 to 1.0 GPa) and temperature (range, 0 to 40° C) using the pulse superposition ultrasonic method. Summary calculated results for a dense fayalite polycrystalline aggregate, based on the HS average of our single-crystal data, are as follows: Vp = 6.67 km/s; Vs = 3.39km/s; K= 127.9 GPa; μ = 50.3 GPa; (∂K/∂P)T = 5.2; (∂μ/∂P)T=1.5;(∂K/∂T)P= −0.030 GPa/K;and,(∂/∂T)P =-0.013 GPa/K (the pressure and temperature data are referred to 25° C and 1 atm, respectively). Accuracy of the single-crystal results was maintained by numerous cross and redundancy checks. Compared to the single-crystal elastic properties of forsterite, Mg2SiO4, the fayalite stiffness constants, as well as their pressure derivatives, are lower for each of the on-diagonal (C ij for which i=j) values, and generally higher for the off-diagonal (C ij for which i≠j) data. As a result, the bulk moduli (K) and dK/dP for forsterite and fayalite are very similar, but the rigidity modulus (μ) and dμ/dP for polycrystalline fayalite are much lower than their forsterite counterparts. The bulk compression properties derived from this study are very consistent with the static-compression x-ray results of Yagi et al. (1975). The temperature dependence of the bulk modulus of fayalite is somewhat greater (in a negative sense) than that of forsterite. The rigidity dependencies are almost equivalent. Over the temperature range relevant to this study, the elastic property results are generally consistent with the data of Sumino (1978), which were obtained using the RPR technique. However, some of the compressional modes are clearly discrepant. The elastic constants of fayalite appear to be less consistent with a theoretical HCP model (Leibfried 1955) than forsterite, reflecting the more covalent character of the Fe-O bonding in the former.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203203
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  • 3
    Electronic Resource
    Electronic Resource
    On the absence of shear mode softening in single-crystal fayalite Fe2SiO4 at high pressure and room temperature (1984)
    Springer
    Physics and chemistry of minerals 11 (1984), S. 167-171 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The geophysical importance of the kinetics of the olivine → spinel phase transformation has stimulated considerable interest in the transformation mechanism. Both nucleation-and-growth and diffusionless martensitic models have been proposed. It has recently been suggested that a martensitic transformation (effected by partial dislocations associated with the (100) [001] slip system) would probably be accompanied by premonitory pressure-induced softening of the shear moduli c 55 and c 66. We have explored this possibility by measurement of the modulus c 55 for a single crystal of fayalite over a pressure range of 3 GPa (at 295 K) by ultrasonic interferometry. The variation of c 55 with pressure is described by a quadratic with the parameters (c 55)0=46.90±0.04 GPa, (∂c 55/∂P)0=1.715±0.004 and (∂2 c 55/∂P 2)0=−(0.136±0.003) GPa−1 where the subscript ‘0’ refers to atmospheric pressure and 295 K. The first pressure derivative is comparable with those for forsterite and ∼Fo90 olivine in spite of the much greater proximity of fayalite to the olivine⇌spinel phase boundary. The absence of pronounced pressure-induced shear mode softening in this study, along with similar results from a recent ultrasonic study of polycrystalline fayalite under conditions of simultaneous high pressure and high temperature, weakens the case for a martensitic olivine⇌spinel transformation mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387847
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  • 4
    Electronic Resource
    Electronic Resource
    Growth and properties of strontium cobaltate single crystals (1978)
    Springer
    Journal of materials science 13 (1978), S. 519-522 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Single crystals of strontium cobaltate with oxygen-deficient composition have been prepared by the floating-zone method using a lamp image furnace. Chemical and X-ray analyses showed that the composition was SrCoO2.70 with a doubled perovskite structure of cubic cells, a 0=7.710±0.001 Å. The crystal was ferromagnetic and its Curie temperature was 150 K. The effective Bohr magneton per ion of Co4+ was 1.21, suggesting that Co4+ is almost in the low spin state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541801
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  • 5
    Electronic Resource
    Electronic Resource
    Preferentially orientated precipitation in MnTiO3 single crystals (1981)
    Springer
    Journal of materials science 16 (1981), S. 1310-1316 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Preferentially orientated precipitation of α-TiO2 (rutile) needles in single crystals of MnTiO3 grown by a floating-zone method under a controlled atmosphere of oxygen fugacity was studied. Optical microscopy and X-ray analysis revealed that the orientation relation between the α-TiO2 precipitates and the MnTiO2 matrix is: {000 1}MnTiO3// {111}α-TiO2 and 〈11¯20〉MnTiO3// 〈110〉α-TiO2. The precipitation phenomenon was explained by introducing a nucleation and growth mechanism which was experimentally supported by heat treating experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01033847
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  • 6
    Electronic Resource
    Electronic Resource
    Phase equilibrium of the Cu-Fe-O system under Ar, CO2 and Ar+0.5% O2 atmospheres during CuFeO2 single-crystal growth (1996)
    Springer
    Journal of materials science 31 (1996), S. 5657-5663 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Phase relations of CuFeO2 during crystal growth under Ar, CO2 and Ar+0.5% O2 surrounding atmospheres have been investigated using scanning electron microscopy together with electron probe microanalysis and X-ray powder diffraction. CuFeO2 was found to partially decompose into Fe2O3 and Cu2O before melting and the crystal growth process was by means of Cu2O-solvent movement. Under Ar and CO2 atmospheres, Cu2O was found to be further reduced to metallic copper, and under CO2 more severe reduction of copper was observed. No copper reduction could be found under an Ar+0.5% O2 surrounding atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01160811
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  • 7
    Electronic Resource
    Electronic Resource
    Shock-induced phase change in BaZnGeO4 crystals (1983)
    Springer
    Physics and chemistry of minerals 10 (1983), S. 16-20 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Shock-loading experiments are performed on single-crystal specimens of BaZnGeO4 (BZG) between 13 and 51 GPa using a propellant gun and a two-stage light gas gun. Observation by an optical microscope reveals that all the shocked specimens are made of fragmented blocks of 10 ∼ 100 μm in size. X-ray analyses indicate that the samples shocked to pressures above 41 GPa became a polycrystalline state of BZG with a weakly textured structure. A small amount of dissociation products of BaGeO3 (pyroxene type) and ZnO (wurtzite type) are detected in this pressure range. Between 27 and 19 GPa, a new phase which is thought to be produced by considerable deformations in the ring structure consisting of ZnO4 and GeO4 tetrahedra is observed. Below 19 GPa, shocked specimens are brought into a well aligned mosaic structure, but no significant change in the crystal structure is detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01204321
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  • 8
    Electronic Resource
    Electronic Resource
    Growth and properties of BaZnGeO4 crystals (1980)
    Springer
    Journal of materials science 15 (1980), S. 2612-2618 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Single crystals of BaZnGeO4 have been grown by the Czochralski pulling method from a stoichiometric melt of barium, zinc and germanium oxides. The crystals were colourless, up to 24 mm in diameter and 35 mm length, and their composition corresponded to the formula Ba0.978Zn0.986Ge1.018O4. X-ray diffraction analysis revealed that the crystal structure was a modified BaAl2O4 type with the hexagonal cell parameters of a 0=92.97 nm and c 0=352.84 nm. Phase transitions were observed at 520 K and 1108 K from measurements of DTA, thermal dilatometry and dielectric constants, and by high temperature X-ray precession photography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00550767
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  • 9
    Electronic Resource
    Electronic Resource
    Growth of Co1−xFexTiO3 single crystals (1983)
    Springer
    Journal of materials science 18 (1983), S. 894-898 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Single crystals of Co1−x Fe x TiO3 (1⩾x⩾0) solid-solution were grown by the floatingzone method using a lamp-heated furnace. Boules averaged 7 mm diameter and 40 to ∼70mm long and were found to be homogeneous as to the value ofx in 80 to ∼90% of the total length. Atmosphere control, employing a mixed gas flow of CO2 and H2, was essential for obtaining high-quality cyrstals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00745588
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  • 10
    Electronic Resource
    Electronic Resource
    High temperature creep in a 2-3-4 garnet: Ca3Ga2Ge3O12 (1999)
    Springer
    Journal of materials science 34 (1999), S. 4783-4791 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract High temperature plastic deformation in a single crystal of a 2-3-4 garnet, Ca3Ga2Ge3O12, was investigated. A Czochralski-grown single crystal of Ca3Ga2Ge3O12 was deformed in compression in air along 〈100〉 or 〈110〉 at temperatures of 1472 to 1573 K (T/Tm = 0.90–0.96). The samples show higher resistance to creep than other 3-3 garnets, namely the flow stress at the strain-rate of 4 × 10− 6 s− 1 is ∼200–400 MPa in this temperature range. The TEM observations of dislocation microstructures show little evidence of climb and plastic deformation in this garnet appears to occur exclusively by dislocation glide, using mostly the 1/2〈111〉{110} slip systems. Dislocations with b = 〈100〉 are frequently observed but they are interpreted as products of dislocation reactions among 1/2〈111〉. The single crystal used contained a number of precipitates that grew during annealing and also during deformation. These precipitates act as sources for dislocations but no evidence for their significant effects on creep strength is observed. The normalized flow law of Ca3Ga2Ge3O12 is similar to other 3-3 oxide garnets (e.g., YAG, GGG), but in contrast to 3-3 garnets, the more stable and hence less mobile dislocations have a large edge component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004695307022
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